1. Field of the Invention
This invention relates, generally, to boat lifts. More particularly, it relates to a boat lift that requires fewer pilings than a conventional boat lift.
2. Description of the Prior Art
A boat is typically lifted from water by positioning a cradle below the surface of the water, positioning a floating boat above the cradle, and lifting the cradle out of the water. A typical cradle is square or rectangular in configuration, and typically includes a pair of longitudinally disposed, transversely spaced apart frame members that are interconnected to one another at their respective opposite ends by transversely disposed braces. Cable-engaging pulleys are mounted at opposite ends of each frame member and overhead winches, mounted on pilings or other suitable support surfaces, are used to raise and lower the frame members.
A conventional boat lift includes four pilings that are driven into a sea bed adjacent a pier, wharf, or dock in a generally square or rectangular array. A first set of two pilings is positioned close to the dock and the second set of two pilings is positioned away therefrom by a distance substantially equal to the width of a boat and a reasonable amount of clearance space. A first winch surmounts the first or inboard set of pilings and a second winch surmounts the second or outboard set.
A boat is positioned between the inboard and outboard pilings such that its longitudinal axis is substantially parallel to a first centerline drawn through the first set of pilings and therefore substantially parallel to a second centerline drawn through the second set of pilings.
Pile driving is an expensive and time-consuming procedure. When the cost of winches, cables, pulleys and motors is added to the cost of the pilings and the boat cradle, a boat lift capable of lifting a five thousand pound boat from the water can cost about twenty five hundred dollars. Consumers will pay only about three thousand for such lifts; accordingly, the profit margin is low and as a result few companies are willing to serve the market. Profit margins increase as the pilings and winches become larger and more powerful, respectively, so most companies serve boat owners having large vessels. Clearly, there is a need for a boat lift that substantially reduces the cost of a five thousand pound boat lift.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how such a boat lift could be built.
The longstanding but heretofore unfulfilled need for a boat lift of substantially reduced manufacturing costs is now met by a new, useful, and nonobvious boat lifting apparatus. The novel structure includes a pair of outboard pilings disposed in longitudinally spaced apart relation to one another, a single inboard piling disposed in transversely and equidistantly spaced apart relation to said pair of outboard pilings, and a cradle disposed between said pair of outboard pilings and said single inboard piling. The outboard pilings are spaced apart from the inboard piling by a distance sufficient to accommodate a boat therebetween when the longitudinal axis of symmetry of the boat is in substantially parallel relation to the outboard pilings.
A first lifting means, supported by the pair of outboard pilings, is provided for lifting an outboard end of the cradle means and a second lifting means, supported by said inboard piling, is provided for lifting an inboard end of the cradle means. In this way, a boat positioned between said pair of outboard pilings and said single inboard piling is lifted upwardly when the outboard and inboard ends of the cradle are lifted upwardly by the outboard and inboard lifting means, respectively.
The cradle includes an elongate brace, a truncate plate, a leading frame and a trailing frame. The elongate brace and the truncate plate are disposed in parallel, transversely spaced apart relation to one another. The leading frame is disposed in interconnecting relation between a first end of the elongate brace and a first end of the truncate plate, and the trailing frame is disposed in interconnecting relation between a second end of the elongate brace and a second end of the truncate plate. Accordingly, the leading and trailing frames are disposed in converging relation to one another as they extend from the outboard pilings to the inboard piling. The angle of convergence is determined by respective lengths of the elongate brace and the truncate plate.
An equalizer assembly is mounted in closely spaced, parallel relation to the truncate plate. The first lifting means is mounted on said outboard pilings and is adapted to lift respective outboard ends of the leading and trailing frame members. The second lifting means is mounted on the single inboard piling and is adapted to lift the equalizer assembly. The equalizer assembly is rotatably mounted at its mid-point to the truncate plate.
An equalizer assembly is mounted in closely spaced, parallel relation to the truncate plate. The first lifting means is mounted on said outboard pilings and is adapted to lift respective outboard ends of the leading and trailing frame members. The second lifting means is mounted on the single inboard piling and is adapted to lift the equalizer assembly. The equalizer assembly is rotatably mounted at its mid-point to the truncate plate.
The elongate brace is formed of two parts that are slideably adjustable with respect to one another and lockable into a plurality of functional positions of adjustment.
The first lifting means includes a reversible motor means and an elongate rotatably mounted drum connected in driven relation to the motor means. A first cable has a first end coiled about the drum and a second end of the first cable is secured to the first end of the leading frame. A second cable has a first end coiled about the drum, and a second end of the second cable is secured to the first end of the trailing frame so that rotation of the drum in a first direction lifts the respective first ends of the leading and trailing frame and rotation of the drum in a second direction lowers the respective first ends of the leading and trailing frame.
The second lifting means means includes a reversible motor means and a truncate rotatably mounted drum connected in driven relation to the motor means. A first cable has a first end coiled about the drum and a second end of the first cable is secured to a first end of the equalizer assembly. A second cable has a first end coiled about the drum and a second end of the second cable is secured to the second end of the equalizer assembly so that rotation of the drum in a first direction lifts said respective first ends of the leading and trailing frame and rotation of the drum in a second direction lowers the respective first ends of the leading and trailing frame.
An important object of this invention is to provide a low cost boat lift capable of lifting a five thousand pound boat.
A closely related object is to achieve the foregoing object by providing a boat lift that requires a support structure that includes only three pilings.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.